Adds name with permissions mode to the tar, yielding io for writing the file. The digest_algorithm is written to a read-only name.sum file following the given file contents containing the digest name and hexdigest separated by a tab.
The created digest object is returned.
Adds name with permissions mode to the tar, yielding io for writing the file. The signer is used to add a digest file using its digest_algorithm per add_file_digest and a cryptographic signature in name.sig. If the signer has no key only the checksum file is added.
Returns the digest.
Checks if there are duplicate links with the same type and hreflang attributes that have an alternate (or empty) rel attribute
Raises a TooMuchTagError if there are duplicates found
Establish the OpenSSL::SSL::SSLContext with the configuration parameters provided.